1. Field of the Invention
The present invention relates to a motor vehicle closure hinge having a pivot axis with spring biasing provided by a laterally coiled spring to prop the closure.
2. Background Art
Many previously known vehicle closure hinges such as those used for engine compartment hoods and trunk lids often include spring biasing to assist displacement of the heavy panel which is displaced about a pivot axis at one end of the panel. However, a spring biasing assist force sufficient to maintain the closure in a fully open position is often provided by additional structure such as a prop rod, gas struts or the like that resists closure of the closure panel by the weight of the panel acting in a moment of arm about the pivot axis or force transfer through a linkage.
One method to provide the spring biasing has been to use the torsion rods that can be routed across the car. However, while such spring biasing can be strong enough to resist closure, since the entire length of the torsion rod provides spring biasing force, the elongated torsion rods can obstruct and form a substantial impediment to the access through the opening or within the compartment covered by the closure panel. Other improvements to spring design, such as gas powered struts or powerful springs often require multiple installation steps since the spring biasing force unit must be separately installed to assist a conventional hinge structure. Such improvements substantially increase the difficulty of production, rendering the use of such components prohibitively expensive because they add production steps as well as additional pieces and mass to the vehicle. In the case of a gas strut power source, in a closed position the line up force in the strut is directed to the hinge pivot, thus forcing the pivot to endure high loading that shortens useful life of the original installation. Also, the life of a gas strut is both time-dependent and cycle-dependent, making it much less durable than a steel spring.
Moreover, once the design and the spring force has been determined for a particular application, the hinge designs may not be readily incorporated into other vehicles having differently sized, weighted or balanced mass or center of gravity than the installation for which it was designed. Rather, the alternative closures need specially designed linkage and/or biasing structures for each particular closure panel type, thereby substantially multiplying the number of assemblies and production pieces that must be made and inventoried by automobile manufacturers and dealers trying in order to accommodate production and repair of the entire product lines of vehicles.
A previously known attempt to address the problems discussed above involves the use of a single pivot arm as part of a four bar link assembly and integral radially wound clock spring. However, while the clock spring may integrate spring biasing force to a hinge mechanism, such springs and require an extremely large envelope both vertically as well as fore-and-aft accommodate the four bar linkage. As a result, these known mechanisms are suitable only for large vehicles, such as trucks. Moreover, alternative designs have been complex, requiring numerous parts and assembly operations, the addition of parts rendering the hinge relatively heavy, and thus have not found favor in many production applications due to the large expense compared to more conventional systems.